If you thought the Basin Reserve flyover looked a bit plain in artists' impressions, then your eye for detail is spot on.

Architects involved in the $90 million project's design have revealed they intentionally opted for a flyover that would mould into the surrounding heritage area, rather than stand out with an "iconic" design.

Megan Wraight, who co-led the flyover's urban design team, told its board of inquiry hearing yesterday that the latter option would not have been appropriate.

"The most appropriate form of structure is considered to be a high-quality, low-profile, multi-span structure that crosses the valley in an uncomplicated but elegant manner."

A four-member board of inquiry is deciding whether the New Zealand Transport Agency's plan to build a two-lane highway flyover 20 metres north of the Basin should get resource consent.

Ms Wraight told them the flyover had been designed to "complement rather than compete with" the Basin Reserve, National War Memorial, carillon and Government House.

The design team believed it achieved that by extending a soon-to-be-constructed park from the National War Memorial to Cambridge Terrace, where it would meet a wetland in front of a new players' pavilion at the Basin's northern entrance.

Extensive planting of native trees would line the journey. Three large trees, including a listed elm tree, would disappear to accommodate a new roading layout but 15 new trees had been proposed, she said.

Lawyer Philip Milne, appearing for opposition groups the Architecture Centre and Newtown Residents Association, pointed out public feedback on the project was not sought until after the agency had eliminated all options except two flyover designs.

He questioned how Ms Wraight knew what the public considered "pleasant" design features, given she had not asked them.

Ms Wraight agreed public consultation would have helped shape her perception, but her design had been informed by extensive consultation with the Transport Agency and Wellington City Council, as well as her decades of experience.

In documents presented to the board, Ms Wraight said a 55m-long pavilion provided the best balance of blocking the flyover from view inside the Basin and not ruining views outside it.

But under cross-examination she admitted she could live with an extra 10 metres.

Lawyer Kerry Anderson, representing the city council and Basin Reserve Trust, said anything less than a 65m-long pavilion could expose cricketers to views of traffic on the flyover.

"Risks shouldn't really be taken with the Basin's ability to host test cricket," she said.